STEREOSELECTION AT THE STEADY-STATE - GROUP SELECTIVE RADICAL CYCLIZATIONS OF SUBSTRATES CONTAINING 2 RADICAL PRECURSORS AND ONE RADICAL ACCEPTOR

The kinetic model for compound stereoselection presented in previous p aper is verified experimentally by conducting a series of radical cycl izations of lo-2-(halomethyl)propyl)cycloalk-2-enecarboxylates with tr ibutyltin hydride and measuring the ratios of products. Cyclization ra te constants are abstracted from the data by an analysis that minimize s total error, and these rate constants compare favorably with rate co nstants that we measured directly on the corresponding monohalides. Tr ansition state modeling was used to interpret the initial round of res ults and to design two new systems, one of which was predicted to cycl ize with higher selectivity than the parent and the other of which was predicted to cyclize with reverse selectivity. These substrates beari ng 4-tert-butyl groups were synthesized, and the experimental results verified the computational predictions.